How to access data in three tier architecture?

Steps:

1.Add a class in your application. Name it ‘clsDataAccessLayer’.
2.Add following code within class.
public class clsDataAccessLayer
{
private SqlConnection sqlCon;
private SqlDataAdapter sqlDa;
private DataSet dsResult;

public SqlConnection Connection()
{
sqlCon = new SqlConnection();
sqlCon.ConnectionString = ConfigurationSettings.AppSettings["Main.ConnectionString"].ToString();
return sqlCon;
}

public DataSet GetResults(string strQuery)
{
try
{
sqlCon = Connection();
sqlCon.Open();
sqlDa = new SqlDataAdapter(strQuery, sqlCon);
dsResult = new DataSet();
sqlDa.Fill(dsResult);

return dsResult;


}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
finally
{
sqlCon.Close();

}
}
}

3.From your UI layer where you want to display the data.
Call the method ‘GetResults’, Which will return a dataset.Bind this dataset where you want to display this data. Example gridview.